I really wasnt expecting this to happen from just one side...
You can see a the shadows of various buildings at different points, moving *counterclockwise* across the screen. Shadows move in a clockwise direction in the Northern Hemisphere.
This, by the way, is how we came up with "clockwise" - shadows moving in that direction meant that sundials have to be laid out in that direction, and the design of clocks derived from that of sundials.
To be even more pedantic, an exception also occurs north of the Arctic Circle during polar night, when there are no shadows cast by the sun ;)
But it has snow, the sun is shining, and the caption says Lake Michigan, so I'm pretty sure it's just the calving of an ice sheet playing backwards.
@khird
Ahh, I missed your point that it was an ice sheet calving... that would make sense yea.
@datatitian